<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>首页</title>
    <script src="js/first.js" type="application/javascript"/>
</head>
<body>
<script type="application/javascript">
    alert("hello,js!");
</script>
<a href="javascript:alert('直接运行js')">哈哈哈</a>

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</body>
</html>